Fuel composition

ABSTRACT

A liquid fuel composition that has as its sole consituents, particulate coal and water. The particulate coal and water are mixed to form a homogeneous slurry that can be handled, stored, pumped and burned in substantially the same manner as conventional liquid fuels. The coal and water in the slurry have the relative proportions of between 54 and 69 per cent by volume coal and 46 to 31 per cent by volume water. The coal particles have a size distribution so that substantially all of the particles pass through a 4 mesh Tyler Standard Screen and between 18 and 33 per cent by weight pass through a 325 mesh Tyler Standard Screen. Less than 60 weight per cent of the coal particles have a size that remains on a 28 mesh Tyler Standard Screen and the remaining coal particles have a size that passes through a 28 mesh Tyler Standard Screen and remains on a 325 mesh Tyler Standard Screen.

United States Patent 1 1 1111 3,762,887

Clancey et al. I 1 Oct. 2, 1973 FUEL COMPOSITION 3,341,256 9/1967 Adams..44 51 3,359,040 12/1967 E r 44/51 [751 lm'emmsl James Chm"; mm 13,124,086 3 1964 Sa g e et al. 44 51 both of Pittsburgh, Pa.; Thomas J.Regan Mamnvme V Edward Primary Examiner-Daniel E. Wyman wasp San RafaelAssistant Examiner-Mrs. Y. H. Smith Assignee: Consolidation CoalCompany, Attrney-D. FOWlCl', Jr. and Stanley Price, Jr.

Pittsburgh, Pa.

[22] Filed: Dec. 14, 1970 {\FSTRACT A I1qu1d fuel compositlon that hasas its sole cons1tu- PP N 98,037 1 ents, particulate coal and water. Theparticulate coal Related Us Application Data and water are mixed to forma homogeneous slurry that can be handled, stored, pumped and burned insubstan- I63] Commuauon of 1966 tially the same manner as conventionalliquid fuels. The

abandoned, which is a continuation-in-part of Ser, No.

229,423 Oct 9, 1962 abandoned. coal and water in the slurry have therelative proportions of between 54 and 69 per cent by volume coal and 52us. (:1. 44/51 46 Per by vlume The Coal P [51] 1 Clm 1/32 have a sizedistribution so that substantially all of the [58] Field 6: Search44/51; 252/31; Particles Pass 4 mesh Tyler Standard Screen 100/7 75 andbetween 18 and. 33 per cent by weight pass through a 325 mesh TylerStandard Screen. Less than 60 wieght [56] References Cited per cent ofthe coal particles have a size that remains on a 28 mesh Tyler StandardScreen and the remaining UNITED STATES PATENTS coal partilces have asize that passes through a 28 mesh 2,233,323 lgliller Tyler StandardScreen and remains on a 325 mesh rowne 728,855 5 1903 Browne 44 51 TylerStandard Screen 3,168,350 2/1965 Phinney et al. 44/51 4 Claims, 1Drawing Figure VISCOSITY. v's FINES LEVEL VISCOSITY BROOKFIELD 6 I I 1 I1 I I 1 5 I0 I5 3O WEIGHT- THROUGH 325 MESH PAIENIEDII" 3.762.887

VISCOSITY V'S FINES LEVEL VISCOSITY BROOKFIELD 5 I 1 I' I J 5 IO I5 2025 3O 35 WEIGHT 73 THROUGH 3 25 MESH INVENTORS J.A. PHINNEY E.J. WASPT.J. REGAN J. T. CLANCEY NEW FUEL COMPOSITION This application is acontinuation of our copending application Ser. 'No. 518,425, filed Jan.3. 1966, entitled A New Fuel Composition," now abandoned which in turnis a continuation-in-part of application Ser. No. 229,423, filed Oct. 9,1962, entitled -A New Fuel Composition," which is now abandoned.

This invention relates to anew composition of matter which is suitablefor use as a liquid fuel, and, more particularly, to a coal-water slurrywhich has the characteristics essential to use as a liquid fuel forcyclone burners, and the like. i

The primary object of this invention is to provide a coal-water slurrythat can be handled, stored, pumped, and burned as a liquid fuel.

Other objects of this invention will become apparent as the invention ismore fully hereinafter described.

In accordance with our invention, we have provided a coal-water slurry,that is,"a mixture of water and finely divided coal, which simulates afuel oil in the following respects:

l. lts composition is homogeneous and remains substantially so afterbeing stored for days and even months. To the extent there is anysettling of the coal particles, and it is at most slight, the settledphase is homogeneous; that is, little or no size segregation of theparticles occurs duringthe slight settling.

2. It is readily pumped and fedunder control of automatic valves orother liquid control means to a coal conversion unit.

3. It is readily burnedwithout prior removal of the water, for example,in a cyclone burner.

The new liquid fuel of our invention has the following composition. Itconsists essentially of finely divided coal and water in the relativeproportions of 54 to 69] For a better understanding of our invention,reference should be had to the following description and to theaccompanying drawing in which is shown a graph f the correlation betweenviscosity and per cent by weight of the coal particles in the coalhaving a size less than 325 mesh Tyler Standard screen.

The preferred method of making the new fuel of our invention isdescribed in U.S. Pat. No. 3,168,350 entitled Transportion of Coal byPipeline issued Feb. 2,

I0 1965, and assigned to the assignee of the present invention;Specifically this method comprises blending a finely divided coal havinga nominal top size between 4 and 28 mesh Tyler Standard screen, obtainedby conventional grindingor crushing means such as rod mills,

5 hammer mills, etc., with a fraction of coal particles passing througha 325 mesh Tyler Standard screen in :such relative proportions as toyield a composition having the size specifications set forth above. Themixture is then stirred to effect homogeneity. The requisite water toyield the desired coal concentration is preferag bly added to thefractions of coal before blending to fa-j cilitate such blending. Anyadditional 4 X 28 mesh parti cles that may be required to meet therecited specifications are also added. The coal concentrations and theisize distributions of the coal of examples of coal-water 'range of'ourinvention and is included for purposes of comparison only.'The coalemployed in these examples was a Pittsburgh Seam coal having a specificgravity of 1.35. With such specific gravity, the range of concentrationsof the coal expressed as per cent by weight rather than per cent byvolume is 62 to 74 (correspondto 54 to 69 per cent by volume set forthabove).

TABLE 1 Percent by weight Example A. B C D E F G H I J K L M N O P Q R 00 0 0 0 0 0 Tr. 0 0 0.4 0 0 0 0 Tr. 0 0

Through 325 mesh 27. 7 30.0 22 27. 5 26. 7 22. 7 24. 4 23.8 23.7 28. 625.8 26.1 27. 5 30. 2 24. 5 30. 6 28.8 11.4

per cent by volume of coal and 46 to 31 per cent by volume of water. Thesize distribution of the finely divided? coal is such that all theparticles will pass through a 4. mesh Tyler Standard screen. Between 18and 33 per? cent by weight of the particles pass through a 325 meshTyler Standard screen. The balance of the coal particles have a range ofsizes between 325. mesh and mesh, with less than ,60'per cent by weightof the total! coal in the range between 28 and 4 mesh.

We prefer, however, that the compositions have a;

coal concentration in the slurry between 57 and 65 per 60 In general thecompositions of this invention have the appearance of a black heavy fueloil such as that commonly referred to as Bunker C fuel oil. Theirspecific gravity is about 1.19. Their net BTU content (that is,, "theBTU content of the coal less the BTUs consumed: in vaporizing the waterpresent is about 9,000 BTU/1b.. of slurry for a Pittsburgh Seambituminous coal which has been subjected to conventional cleaningprocedures.

One of the most important properties of our new fuel is its stabilityupon storage for protrated periods of time. Even on extended periods ofstorage there occurs little or no segregation of sizes, and changes inconcentration are'slight. The following Table 11 illustrates thebehavior of a typical composition (Example A of Table 1) upon standingduring three days in a 25-foot high TABLE ll Thru Cone. On 8 Mgs h8 x 14Mesh. 325 Mes h Top 1st Day 67.7 7 21.1 25.3 Bottom 1st Day 71.1 5.922.7 23.4 Top 3rd Day 70.0 6.6 21.3 25.5 Bottom 3rd Day 71.0 6.1 22.924.0

In general the viscosity of our new fuel is in the range of that of hotBunker C fuel oil. It can be readily pumped in centrifugal or positivedisplacement pumps. The drawing shows graphically a correlation ofviscosity with weight per cent of through 325 mesh particles in thecoal. This correlation is typical of the compositions of our invention,although the minimum may shift somewhat depending upon the precise sizedistribution. The one shown in the drawing was obtained by blending inwater a relatively coarse coal fraction A with a relatively fine coalfraction 8 to yield a final coal concentration of 63 per cent by weightwith varying amounts of through 325 mesh coal to provide samples for theviscosity determinations with the exception of the point on the curvedesignated G. This point represents the viscosity of themixture obtainedby making up a 63 per cent concentration of the coal listed as Example Rin Table I, i.e., a natural grind. The viscosities shown in the drawingare those obtained in a Brookfield Synchro-Lectric Viscosimeter (made bythe Brookfield Engineering Laboratories, Stoughton, Mass.). Our new fuelis a non-Newtonian pseudoplastic fluid, and as such has no ordinaryviscosity. The size distributions of .the two fractions A and B arelisted in Table III below.

TABLE Ill Fraction A Fraction 8 (1: by Weight) by Weight) n 8 mesh 1.2 gOn l4 mesh 13.7 On 28 mesh 29.1 0 On 48 mesh 20.7 0.6 On 100 mesh 13.91.0 On 200 mesh 6.1 4.9 On 325 mesh 3.9 9.6 Trhough 325 mesh 11.4 83.4

We have found the compositions of this invention to be completelysatisfactory as a substitute for fuel oil fed to a cyclone type burner.The burner needs no modification to permit the use of our new fuel. Asan example, a coal-water slurry having the specifications of Example Ain Table I was prepared from a Pittsburgh Seam coal that had a BTUcontent of 13,500 on a moisturefree basis. The coal had the followingproximate analysis (dry basis):

Volatile Matter 388% Fixed Carbon 53.6% Ash 7.6%

The liquid slurry was kept in a storage tank during the period of theburning test, and was withdrawn continuously under the control of aconventional liquid fuel valve. A small amount of circulation comparableto that used in Bunker C fuel oil tanks was maintained in the tank. Thepump used to withdraw the slurry from the tank was a centrifugal pumpnormally used in cyclone burner installations. During the period oftest, i.e., 23 days, the flow of fuel was trouble-free. The performanceof the burner was essentially the same as though fuel oil were beingemployed, allowing for the difference in BTU contents. There was novisual difference between the slurry flame and a fuel oil flame. Thesteam formed by the conversion of the slurry water was discharged fromthe burner in the same manner as the steam formed by combustion.

According to the provisions of the patent statutes, we have explainedthe principle, preferred construction, and mode of operation of ourinvention and have illustrated and described what we now consider torepresent its best embodiment; However, we desire to have it understoodthat, within the scope of the appended claims, the invention may bepracticed otherwise than as specifically illustrated and described.

We claim:

1. A homogeneous composition of matter suitable for use as a liquid fuelconsisting essentially of particulate coal and water in the relativeproportions of 54 to 69 percent by volume of coal and 46m 31 per cent byvolume of water, said particulate coal having a size distributionsubstantially as follows: 0 per cent by weight on 4 mesh Tyler Standardscreen, 18 to 33 per cent by weight less than 325 mesh, less than 60 percent by weight between 4 and 28 mesh, and the balance in the size rangeof 28 to 325 mesh.

2. A homogeneous composition of matter suitable for use as a liquid fuelconsisting essentially of particulate coal and water in the relativeproportions of 57 to per cent by volume of coal and 43 to 35 per cent byvolume of water, said particulate coal having a size distributionsubstantially as follows: 0 per cent by weight on 4 mesh Tyler Standardscreen, 22 to 28 per cent by weight less than 325 mesh, 20 to 30 percent by weight between 4 and 28 mesh, and the balance in the size rangeof 28 to 325 mesh.

3. A homogeneous composition of matter suitable for use as a liquid fuelconsisting essentially of particulate coal having a specific gravity ofabout 1.35 and water in the relative proportions of about 68 per cent byweight of said coal and about 32 per cent by weight of water, saidparticulate coal having a size distribution substantially as follows: 0per cent on a 4 mesh Tyler Standard screen, about 28 per cent by weightless than 325 mesh, about 25 per cent by weight between 4 and 28 mesh,and the balance in the size range of 28 to 325 mesh.

4. A composition of matter suitable for use as a liquid fuel consistingessentially of particulate coal having a specific gravity of about 1.35and water in the relative proportions of about 68 per cent by weight ofsaid coal and about 32 per cent by weight of water, said particulatecoal having a size distribution substantially as follows:

2. A homogeneous composition of matter suitable for use as a liquid fuelconsisting essentially of particulate coal and water in the relativeproportions of 57 to 65 per cent by volume of coal and 43 to 35 per centby volume of water, said particulate coal having a size distributionsubstantially as follows: 0 per cent by weight on 4 mesh Tyler Standardscreen, 22 to 28 per cent by weight less than 325 mesh, 20 to 30 percent by weight between 4 and 28 mesh, and the balance in the size rangeof 28 to 325 mesh.
 3. A homogeneous composition of matter suitable foruse as a liquid fuel consisting essentially of particulate coal having aspecific gravity of about 1.35 and water in the relative proportions ofabout 68 per cent by weight of said coal and about 32 per cent by weightof water, said particulate coal having a size distribution substantiallyas follows: 0 per cent on a 4 mesh Tyler Standard screen, about 28 percent by weight less than 325 mesh, about 25 per cent by weight between 4and 28 mesh, and the balance in the size range of 28 to 325 mesh.
 4. Acomposition of matter suitable for use as a liquid fuel consistingessentially of particulate coal having a specific gravity of about 1.35and water in the relative proportions of about 68 per cent by weight ofsaid coal and about 32 per cent by weight of water, said particulatecoal having a size distribution substantially as follows: